Experimental and Numerical Investigation on Planar Motion Responses of a Single Point Moored Shuttle Tanker in Waves

2019 ◽  
Author(s):  
Ning He ◽  
Cheng Zhang ◽  
Zhuang Kang ◽  
Youwei Kang ◽  
Changhong Wang
Keyword(s):  
Model Test ◽  
Deep Water ◽  
Oil And Gas ◽  
Single Point ◽  
Diffraction Theory ◽  
Line Length ◽  
Plane Motion ◽  
Mooring Line ◽  
Motion Responses ◽  
Motion Characteristics

Abstract In order to ensure the safety of the single point moored shuttle tanker in waves, the numerical model of a shuttle tanker moored with a fixed point was established on the basis of radiation / diffraction theory and pressure integral method in this paper, which was further checked by a series of model tests. Then the plane motion characteristics of the tanker like fishtailing oscillation were analyzed by applying the combined approach of numerical simulation and model test. On this basis, the effects of wave and ballast conditions as well as mooring line length and stiffness on the plane motion of the single point moored tanker were investigated by means of model test. Overall, the research can provide a reference for the design and safety assessment of deep-water offloading system, and give the technical support for the engineering development of deep-water oil and gas projects.

Double Acting Tanker: Experiences from Model Tests and Sea Trials

2005 ◽  
Vol 219 (3) ◽  
pp. 109-119 ◽  
Author(s):  
P Trägärdh ◽  
P Lindell ◽  
N Sasaki
Keyword(s):  
Model Test ◽  
Oil And Gas ◽  
Single Point ◽  
Open Water ◽  
Model Tests ◽  
Water Model ◽  
Research Centre ◽  
Sea Trial ◽  
Cavitation Performance ◽  
Ice Conditions

The acronym DAT stands for double acting tanker, a concept where the ship is designed to run astern in heavy ice conditions while remaining hydrodynamically efficient for ahead propulsion in open water conditions. Two large aframax DATs - 106.000 dwt (deadweight tons) each - have been delivered by Sumitomo Heavy Industries to Fortum Oil and Gas OY. They are the first crude carriers built according to the DAT principle and also the first using pod propulsion from the beginning (Fig. 1). They will also be the world's largest crude carriers with ice class 1A super and are primarily intended for year-round transportation of North Sea crude to Fortum's refineries in the Gulf of Finland. The ships were appointed ‘ship of the year’ in Japan in 2003. SSPA was contracted by Sumitomo Heavy Industries to perform model tests. A comprehensive open water model test programme was used to investigate aspects of resistance and propulsion, manoeuvring, and cavitation performance. As the ship is designed to operate both in ahead and astern conditions for prolonged periods of time, most tests were performed both ahead and astern. Also, a simulation study of dynamic positioning at buoy or floating production, storage offshore (FPSO) loading was made by SSPA. Comprehensive tests of the ship's performance in ice were performed in the ice tank at MARC (Masa-Yards Artic Research Centre). The eight-month model testing and development campaign resulted in a ship with excellent propulsion and manoeuvring performance, especially with regard to the high ice class. Sea trials carried out with ship in August 2002 confirmed the results of the model test. Interesting experiences of the model test campaign and comparison between model test and sea trial results are presented, as well as some examples of single-point mooring simulations.

APPLICATION OF NUCLEONIC INSTRUMENTS IN SEPARATOR PROFILING: KUITO FPSO CASE STUDY

2006 ◽  
Vol 46 (1) ◽  
pp. 405
Author(s):  
B. Beinart
Keyword(s):  
Deep Water ◽  
Oil And Gas ◽  
Produced Water ◽  
Single Point ◽  
Oil Production ◽  
Fluid Interface ◽  
Start Up ◽  
Fluid Levels ◽  
Separation Problems

The Kuito field lies in the offshore Cabinda Province, Angola. Kuito was Angola’s first deep-water oil and came on stream in December 1999. Kuito oil is produced via an FPSO. Kuito oil ranges 18–22 API. The FPSO has threephase, horizontal, gravity separation vessels that are used to separate oil and gas from unwanted produced water and solids prior to transportation. The production separators were designed with traditional, single point transmitters for measurement of the fluid interface and overall fluid levels. These were capacitance type instruments mounted inside the vessels in stilling wells.Following production start-up, separation problems began to emerge; these were manifested in numerous process upsets and shutdowns. Kuito oil can form emulsions quickly, and calcium naphthenate is produced at higher temperatures. If allowed to cool, it solidifies. The point instrumentation was unable to detect these emulsion and naphthenate layers resulting in the instrumentation becoming fouled and ceasing to function. The separators were operated ‘blind’, using tri-cocks located on the side of the vessel, and as the instrumentation was installed in stilling wells inside the vessel, it was impossible to maintain them without shutting down and depressurising the vessels. This paper describes how nucleonic profiling instruments were retrofitted to the vessels and shows how their operation was able to identify the different layers within the separators. This enabled the time of oil production to be increased and allowed the pro-active use of effect chemicals such as emulsion breakers and defoamers to be applied before the plant became unstable.

scholarly journals Structural Reliability Based Dynamic Positioning of Turret-Moored FPSOs in Extreme Seas

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Yuanhui Wang ◽  
Chuntai Zou ◽  
Fuguang Ding ◽  
Xianghui Dou ◽  
Yanqin Ma ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Structural Reliability ◽  
Oil And Gas ◽  
Single Point ◽  
Line Tension ◽  
Mooring Line ◽  
Dynamic Positioning ◽  
Mooring Lines ◽  
Oil And Gas Exploration ◽  
Time Control

FPSO is widely used during the deep-sea oil and gas exploration operations, for which it is an effective way to keep their position by means of positioning mooring (PM) technology to ensure the long-term reliability of operations, even in extreme seas. Here, a kind of dynamic positioning (DP) controller in terms of structural reliability is presented for the single-point turret-moored FPSOs. Firstly, the mathematical model of the moored FPSO in terms of kinematics and dynamics is established. Secondly, the catenary method is applied to analyze the mooring line dynamics, and mathematical model of one single mooring line is set up based on the catenary equation. Thereafter, mathematical model for the whole turret mooring system is established. Thirdly, a structural reliability index is defined to evaluate the breaking strength of each mooring line. At the same time, control constraints are also considered to design a state feedback controller using the backstepping technique. Finally, a series of simulation tests are carried out for a certain turret-moored FPSO with eight mooring lines. It is shown in the simulation results that the moored FPSO can keep its position well in extreme seas. Besides, the FPSO mooring line tension is reduced effectively to ensure mooring lines safety to a large extent in harsh sea environment.

Self-Installed Single Column Floater

2004 ◽  
Author(s):  
Frank Chou ◽  
John Chianis ◽  
Xinyu Zhang
Keyword(s):  
Gulf Of Mexico ◽  
Research And Development ◽  
Deep Water ◽  
Oil And Gas ◽  
Geographical Area ◽  
Current Concept ◽  
Motion Responses ◽  
Production Platform ◽  
Single Column ◽  
Exploration And Production

This paper introduces a novel floating production platform concept for exploration and production of oil and gas in ultra deep water. The developmental effort has been supported by ABB in-house research and development budget. This novel production unit is an enhanced version of ABB Self-Installed Single Column Floater (SISCF) concept. This unit is envisioned to be completely assembled at quayside, towed to location, and be installed vertically to its target draft without the need of a major crane vessel. This enhanced feature reduces the wind load on the deck and hull significantly during wet tow as well as alleviates the uncertainty on the duration of an offshore operation, thereby widens the weather window for installation, hook-up and commissioning offshore. The enhanced SISCF (ESISCF) hull consists of four major components i.e., hard tank with center opening, soft tank with telescoping truss members and opening, permanent-stability ring, and three (3) telescoping support columns. During the installation phase, the telescoping columns are used to guide the permanent-stability ring, which provided needed stability in the installation phase. In addition, because of the way center truss being constructed, the hard tank is collapsed (or sit) right on top of the soft tank during wet tow thus reduced the wind arm (almost 100 ft) and wind forces. In its in-place position, ESISCF motion responses in waves are found to be excellent because of its deep draft. The current concept combines the advantages of a spar and a semi-submersible vessel. The paper will detail the concept, and outline the fabrication to installation scenario. The principal dimensions of a typical ESISCF for a given payload will be presented together with its stability and motion responses in waves based on the sea conditions representing a typical geographical area of Gulf of Mexico. The advantages of this concept will be explained in detail.

Wind Induced Nonlinear Response of Coupled Spar Platform

2014 ◽  
Author(s):  
Mohammed Jameel ◽  
Suhail Ahmad ◽  
A. B. M. Saiful Islam ◽  
Mohd Zamin Jumaat
Keyword(s):  
Deep Water ◽  
Oil And Gas ◽  
Wave Force ◽  
Wind Loading ◽  
Coupled Analysis ◽  
Mooring Line ◽  
Wave Direction ◽  
Spar Platform ◽  
Mooring Lines ◽  
Spar Platforms

The oil and gas exploration has moved from shallow water to much deeper water far off the continental shelf. Spar platforms under deep water conditions are found to be the most economical and efficient type of offshore platform. Several Spar platforms installed in the Gulf of Mexico and North Sea proves its suitability for deep water exploration. Accurate prediction of motions of a Spar hull is very important for the integrity and associated costs of the riser/mooring line. The most common approach for solving the dynamics of Spar platform is to employ a decoupled quasi-static method, which ignores all or part of the interaction effects between the platform, mooring lines and risers. Coupled analysis, which includes the mooring lines, risers and platform in a single model, is the only way to capture the damping from mooring lines and risers in a consistent manner. The present coupling is capable in matching the forces, displacement, velocities and acceleration for mooring line with Spar hull at the fairlead position and riser with Spar hull at the riser keel connection. It can handle possible significant nonlinearities. The output from such analyses will be platform motions as well as a detailed mooring line and riser responses. In actual field problems hydrodynamic and aerodynamic loads act simultaneously on Spar platform, mooring lines and risers. In finite element model, the entire structure acts as a continuum. This model can handle all nonlinearities, loading and boundary conditions. The selected configuration of Spar platform is analysed under wave force together with wind loading and its structural response behaviour in steady state is studied. An automatic Newmark-β time incremental approach in ABAQUS/AQUA environment has been implemented to conduct the analysis in time domain. The wind force acting on the exposed part of the platform encompasses mean and fluctuating wind components. The frontal region includes the topside assembly and the spar hull portion above the sea level. High degree of nonlinearities makes the solutions convergence sensitive and it requires large number of iterations, at each time station. Spar responses in surge, heave and pitch along with top tension in moorings are computed. The coupled Spar experiences significant lateral shift along wave direction due to wind loading. Increase in standard deviation shows the participation of wind loading giving higher fluctuations. The CML tension increases for wind loading but the extent of the tension fluctuations under wind loading is not much due to high pretension of mooring line.

NOVEL PRODUCTION CONCEPTS FOR DEEP WATER AND ASSOCIATED HYDRODYNAMIC PROBLEMS

1998 ◽  
Vol 38 (1) ◽  
pp. 855
Author(s):  
K.P. Thiagarajan
Keyword(s):  
Deep Water ◽  
Oil And Gas ◽  
Production Systems ◽  
Gas Production ◽  
Oil And Gas Production ◽  
Cylindrical Structures ◽  
Campos Basin ◽  
Offshore Oil And Gas ◽  
Motion Characteristics ◽  
Offshore Oil

Offshore oil and gas production is now reaching to great depths, in excess of 1000 m, in the Gulf of Mexico and the Campos Basin, offshore Brazil. It will not be long before Australian companies look towards probable reserves in deeper waters that still remain within the Australian exclusive economic zone. Production concepts for deep and ultra deep water thus need to be studied and researched, and a constant watch should be maintained on developments around the world in this area.This paper presents two popular, and constantly evolving, concepts for deep water, namely: tension leg platforms (TLP) and spars. Tension leg platforms have been in existence for about 14 years, and are actively sought for deep water by worldwide operating companies. They are vertically moored by means of taut tethers which present interesting motion characteristics and unique hydrodynamic problems. Spar platforms are currently being installed for production purposes. These are large deep draft cylindrical structures moored by catenary or taut spread mooring systems. Physical details, advantages and limitations of both systems are discussed.While many aspects of these production systems are now understood, there are still several unknowns. Deeper waters translate to newer problems. Potential problems of the future are discussed in this paper, and research needs are highlighted.

A Novel Hybrid Method of Pre-Tension Adjustment of Mooring Lines in the Model Test

2020 ◽  
Author(s):  
Junfeng Du ◽  
Hongchao Wang ◽  
Anteng Chang ◽  
Mingyuan Sun ◽  
Junrong Wang ◽  
...  
Keyword(s):  
Model Test ◽  
Line Tension ◽  
Line Length ◽  
Mooring Line ◽  
Cyclic Process ◽  
Mooring System ◽  
Ideal Model ◽  
Mooring Lines ◽  
Target Value ◽  
The Ideal

Abstract Mooring lines are the most commonly used station-keeping systems for floating platforms, and the pre-tension of the mooring lines has significant effect on the dynamics of floater/mooring system. However, during the model test, which is the most important method for the research on the floater/mooring system, the pre-tension of the designed mooring lines in the basin are always significantly different with the target values of the ideal model due to the error of the manufacture of the mooring lines and positon locating of the anchor point and so on. As a result, the adjustment of the pretension of the mooring lines based on the ideal model is an important task during the model test. The pre-tension is always adjusted by increasing or decreasing mooring line length. While all the mooring lines are connected with the floater and coupled with each other, pre-tension adjustment is an unwarranted and cyclic process which often wastes a lot of time. This paper presents a novel methodology for regulating the mooring line pre-tension based on matrix calculation. The increment matrix of the mooring line tension can be obtained by increasing or decreasing the length of each mooring line in the numerical model. Assuming that the increment the mooring line tension is linear to the change of the mooring line length, the adjustment amount of each mooring line length can be calculated from the difference of the real pre-tension and the target pre-tension. However, the mooring line tension is always nonlinear to the mooring line length. Calculating the increment matrix of the mooring line tension and adjustment of the mooring line length is also a cyclic process until the error of real pre-tension of the model in the basin and target value can meet the accuracy requirement. This method is used in a model of a mooring system with 12 mooring lines which are connected with a semi-submersible platform. The test results show that the pre-tension of mooring lines can be adjusted to the target value quickly based on the method proposed in this paper.

Evaluation of Abrasive Wear of Polymeric Materials Using Single-Pass Pendulum Scratching

2002 ◽  
Author(s):  
Marcelo Torres Piza Paes ◽  
Antonio Marcos Rego Motta ◽  
Lauro Lemos Lontra Filho ◽  
Juliano Ose´ias de Morais ◽  
Sine´sio Domingues Franco
Keyword(s):  
Deep Water ◽  
Wear Mechanisms ◽  
Degradation Mechanism ◽  
Single Point ◽  
Polymeric Materials ◽  
Scratch Resistance ◽  
Wear Behaviour ◽  
Sediment Layer ◽  
Materials Used ◽  
Energy Dissipated

Scratching abrasion due to rubbing against the sediment layer is an important degradation mechanism of flexible cable in deep water oil and natural gas exploitation. The present study was initiated to gain relevant data on the wear behaviour of some commercial materials used to externally protect these cables. So, Comparison tests were carried out using the single-point scratching technique, which consists of a sharp point mounted at the extremity of a pendulum. The energy dissipated during the scratching is used to evaluate the relative scratch resistance. The results showed, that the contact geometry strongly affects the specific scratching energy. Using SEM imaging, it was found, that these changes were related to the operating wear mechanisms. The observed wear mechanisms are also compared with those observed on some cables in deep water operations.

THE SAFETY OF TANKERS AND SINGLE POINT MOORING DURING LOADING OPERATIONS

Transport ◽  
2009 ◽  
Vol 24 (1) ◽  
pp. 54-57 ◽  
Author(s):  
Vytautas Paulauskas
Keyword(s):  
Theoretical Basis ◽  
Oil And Gas ◽  
Single Point ◽  
Offshore Platforms ◽  
Port Facilities

Single point mooring (SPM) is used when typical port facilities cannot be applied. Offshore platforms and terminals producing oil and gas are the places where SPM can be employed. Accidents with SPM equipment and ships occurring during loading or unloading operations are very dangerous and may cause serious losses due to the high prices of tankers and facilities and because of polluting the environment with poisonous materials. Any possibilities of decreasing risk and increasing safety are very important. This paper presents the analysis of dangerous situations with tankers and SPM, discusses theoretical basis for study and makes practical calculations and recommendations on decreasing accidence probability during loading operations.

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